McCool originally worked as a middle school teacher in Palatka, Florida. She joined WWE in 2004 after participating in the WWE Diva Search. In her initial on-screen appearances, she utilized the character of a personal trainer, before changing it to that of a teacher. At The Great American Bash in 2008, McCool became the inaugural WWE Divas Champion, holding the title for approximately five months. She then won the WWE Women's Championship at The Bash in 2009, becoming the first female wrestler to have held both titles. At Night of Champions in 2010, she unified both titles becoming the first and only WWE Unified Divas Champion. McCool held both titles on two occasions, which makes her a four-time champion overall. In November 2010, she was ranked number one in Pro Wrestling Illustrated's Female 50, and she retired the following year.

McCool was then repackaged as "The All-American Diva", where she began accompanying her on-screen friend Chuck Palumbo during matches against Jamie Noble.[1] After a series of matches between the men, Noble won a date with McCool by defeating Palumbo.[1] In the storyline, Palumbo accidentally elbowed McCool during a match,[1] causing her to suffer a concussion.[20] The partnership was dissolved when McCool refused to accept his apology.[1] She then went on to compete in a series of matches with Victoria, Eve Torres, Maryse and Cherry to determine SmackDown!'s top Diva, with McCool winning title.[3]

On the July 4, 2008, episode of SmackDown!, McCool won a Golden Dreams match to face Natalya for the WWE Divas Championship at The Great American Bash. At the event, on July 20, McCool defeated Natalya to become the inaugural WWE Divas Champion.[21] McCool successfully defended the title against Maryse on SmackDown and at the Unforgiven pay-per-view in September, and against Maria on SmackDown in November.[22][23][24] On the December 26 episode of SmackDown!, McCool lost the Divas championship to Maryse.[25] After the match McCool turned heel by attacking Maria, the special guest referee of the match, and blaming her for the loss.[25] In the following weeks, McCool also attacked Eve Torres,[26] resulting in Torres' debut match, which McCool won.[27]

McCool then defeated Gail Kim on the May 22, 2009, taping of SmackDown to become the number one contender for the WWE Women's Championship.[28] A month later at The Bash, McCool defeated Melina — with help from Alicia Fox — to win her first Women's Championship.[1][29] With her win, McCool became the first Diva to have won both the WWE Divas and Women's championships.[30] She retained the championship against Melina in a rematch on July 26 at Night of Champions,[31] and also in a Lumberjill match on the October 2 episode of SmackDown!.[32]

McCool then allied with Layla to form LayCool, and the duo entered a controversial feud with Mickie James, in which LayCool bullied James and made fun of her weight. The feud resulted in a five-on-five elimination tag team match at Survivor Series, which James' team won, when Melina pinned McCool.[33] James then became the number one contender for McCool's WWE Women's Championship at TLC: Tables, Ladders & Chairs, where McCool successfully retained the championship after interference from Layla.[34][35] McCool lost the Women's Championship to James at the Royal Rumble, although she regained it on the February 26, 2010, episode of SmackDown! when special guest refereeVickie Guerrero interfered, to become a two-time Women's Champion.[36][37] On the April 23 episode of SmackDown!, McCool and Layla defeated Beth Phoenix and Mickie James, and attacked Phoenix after the match. This led to McCool losing the championship to Phoenix in an "Extreme Makeover" match at Extreme Rules.[38] On the May 14 episode of SmackDown!, McCool and Layla faced Phoenix in a Women's Championship two-on-one handicap match, in which Layla pinned Phoenix to win the championship.[39] Despite Layla's win, McCool and Layla cut the Women's Championship in half, and the duo were unofficially referred to as the "co-champions".[40]

On the April 8 episode of SmackDown!, dissension began to show between McCool and Layla after they were defeated by Beth Phoenix and Kelly Kelly, due to McCool avoiding being tagged in by Layla, citing a back injury.[47] After more arguing and unsuccessful couples therapy sessions in the following weeks, LayCool officially disbanded.[48] On the April 29 episode of SmackDown, McCool faced Layla in a singles match, which ended in a double countout after the two began brawling. After the match, Layla challenged McCool to a no disqualification and no countout match at Extreme Rules. McCool accepted under one condition, which was that the loser leaves WWE.[49] At Extreme Rules, McCool was pinned by Layla, forcing her to leave WWE.[50]

On January 22, 2018, McCool was honored as part of a segment involving women that contributed to the company's success on the WWE Raw 25 Years special episode.[51] The following week, she was a surprise entrant in the inaugural women's Royal Rumble match at the 2018 Royal Rumble, making the most eliminations in the match at five before being eliminated by Natalya.[52] In October, McCool took part in the all women's pay-per-view, WWE Evolution, by participating in a battle royal. She was eliminated from the match by Ember Moon.[53]

McCool was married to Jeremy Louis Alexander, whom she began dating in high school.[1][60][61] The couple divorced in 2006.[1] She married fellow wrestler Mark Calaway, known professionally as The Undertaker, on June 26, 2010, in Houston, Texas.[62][63] Their first child together, a daughter, was born in August 2012.[64]

McCool is a Christian,[65] and she incorporated Christian crosses on her wrestling attire.[66] She has had several wrestling-related injuries; in November 2007, she fractured her nose during an overseas WWE tour after Victoria's clothesline hit her in the face.[67] She has been hospitalized twice, had two broken ribs, a broken sternum, and a broken xiphoid process.[68] When she chose to leave the WWE, she mentioned that her foot had been injured for two months with a broken toe, torn joint capsules and a torn MCL.[69] In 2016, McCool was diagnosed with skin cancer, and underwent treatment.[70]

^McCool originally injured her back during a WWE European tour. Because of pain in her back, she was unaware of the sternum injury until she went to the hospital for treatment. Tests also revealed that she had an enlarged kidney.[13]